Analyte capturing devices with fluidic ejection devices

ABSTRACT

In one example in accordance with the present disclosure, an analyte capturing device is described. The analyte capturing device includes a first substrate having microfluidic channels disposed therein and a second substrate disposed on top of the first substrate. A chamber is disposed through the second substrate and captures beads therein, which beads adsorb analytes. The analyte capturing device includes at least one fluid ejection device disposed in the first substrate to draw an analyte-containing solution through the beads disposed within the chamber.

BACKGROUND

Analyte concentration is a sample preparation operation used in manychemical analysis operations. For example, concentration ofdeoxyribonucleic acid (DNA) and ribonucleic acid (RNA) is a samplepreparation step in nucleic acid testing. Concentrating the analytesenhances the efficacy and accuracy of subsequent analysis operations.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate various examples of the principlesdescribed herein and are part of the specification. The illustratedexamples are given merely for illustration, and do not limit the scopeof the claims.

FIGS. 1A-1C are diagrams of an analyte capturing device with fluidejection devices, according to an example of the principles describedherein.

FIG. 2 is a flow chart of a method for analyte capturing with fluidejection devices, according to an example of the principles describedherein.

FIGS. 3A-3C are diagrams of an analyte capturing device with fluidejection devices, according to another example of the principlesdescribed herein.

FIG. 4 is a cross-sectional diagram of an analyte capturing device withfluid ejection devices, according to another example of the principlesdescribed herein.

FIG. 5 is a diagram of a method for analyte capturing with the fluidejection devices, according to another example of the principlesdescribed herein.

FIG. 6 is a cross-sectional diagram of an analyte capturing device withfluid ejection devices, according to another example of the principlesdescribed herein.

FIG. 7 is a top view of an analyte capturing device with fluid ejectiondevices, according to another example of the principles describedherein.

Throughout the drawings, identical reference numbers designate similar,but not necessarily identical, elements. The figures are not necessarilyto scale, and the size of some parts may be exaggerated to more clearlyillustrate the example shown. Moreover, the drawings provide examplesand/or implementations consistent with the description; however, thedescription is not limited to the examples and/or implementationsprovided in the drawings.

DETAILED DESCRIPTION

Analyte concentration is a sample preparation operation in many chemicalanalysis operations. For example, concentration of deoxyribonucleic acid(DNA) and ribonucleic acid (RNA) is a sample preparation step in nucleicacid testing. Concentrating the analytes enhances the efficacy andaccuracy of subsequent analysis operations.

There are various ways to concentrate an analyte. As a specific example,certain materials may have an affinity for an analyte and may thereforeattract the analyte. Quantities of this material can be formed intomicroscopic beads and may be included in a solution to adsorb theanalyte to the bead surface.

While using beads in solution is effective at separating the analyte,such systems present certain complications. For example, once drawn tothe beads, the beads themselves should be separated from the rest of thesolution such that the analyte may be removed. One way to separate thebeads is magnetic gathering. In this method, the beads have aparamagnetic core and are pulled from the solution by an externalpermanent magnet. In another example, the beads are separated from therest of the solution based on size differences. For example, a size ofobjects in a biological sample may be between 0.1-1.0 microns whereasthe beads may be between 1-10 microns in diameter. Thus, if a mixturewith the beads and analyte is passed through a filter with pore sizes ofseveral microns, the beads will be trapped while the rest of thesolution will pass through. Since at this stage, the analyte, such asDNA molecules, are still attached to the bead surface, trapping beads ina filter concentrates DNA.

While such operations are effective at concentrating an analyte within asolution, improved operations in this field would increase efficacy andsubsequent operation accuracy. Accordingly, the present specificationdescribes a system and method for concentrating analyte usinganalyte-adsorbing beads, and for separating the analyte-adsorbing beadsfrom the rest of the sample fluid. Specifically, the presentspecification relies on fluid ejection devices and a mesoscopic fluiddelivery chamber to capture the analyte-adsorbing beads.

The fluid ejection devices expel waste carrier fluid while the analyteis retained within a chamber. To eject the fluid, the fluid ejectiondevices include a number of components. Specifically, the fluid to beejected is held in an ejection chamber. A fluid actuator operates todispel the fluid in the ejection chamber through an opening. As thefluid is expelled, a negative capillary pressure within the ejectionchamber draws additional fluid into the ejection chamber, and theprocess repeats. In this example, the ejection chamber has microscaledimensions. Fluid is fed to the ejection chamber via a fluid feedchannel, which is larger, for example having mesoscale dimensions.

The chamber of the analyte capturing device has dimensions toaccommodate beads having a diameter sufficiently large that they aretrapped in the chamber and cannot enter the microfluidic passageways northe ejection chamber. During operation, as the ejector actuates, thesolution is pulled through the chamber where the beads are stored. Assuch, the analyte adheres to the surface of the beads and the rest ofthe solution, i.e., a carrier fluid, passes through to the ejectionchamber to be expelled. Accordingly, as an entire sample is treated, thecarrier fluid is expelled through the fluid ejection device and theanalyte is left behind in the chamber. From here, the analyte can besubsequently ejected through the fluid ejection device onto a surface orinto a container. In another example, the analyte is routed to anotherchamber where it can be further analyzed.

Specifically, the present specification describes an analyte capturingdevice. The analyte capturing device includes a first substrate havingmicrofluidic channels disposed therein and a second substrate disposedon top of the first substrate. In this example, a chamber is disposedthrough the second substrate to capture beads therein. The beads mayadsorb analytes. The device also includes at least one fluid ejectiondevice disposed in the first substrate to draw an analyte-containingsolution through the beads disposed within the chamber.

The present specification also describes a method. According to themethod, beads that adsorb analytes are captured in a mesofluidic chamberof an analyte capturing device. A microfluidic fluid ejection device isactivated to generate a flow through the mesofluidic chamber and acarrier fluid is expelled from the analyte capturing device.

In another example, the analyte capturing device includes a planarmicrofluidic substrate having microfluidic channels disposed therein anda planar silicon substrate disposed on top of the planar microfluidicsubstrate. The analyte capturing device also includes at least onemesoscale chamber disposed through the planar silicon substrate tocapture beads therein, which beads are to adsorb analytes. The analytecapturing device also includes microscale fluid ejection devicesdisposed in the planar microfluidic substrate to draw ananalyte-containing solution through the beads disposed within thechamber. In this example, each fluidic ejection device includes 1) anejection chamber to hold a volume of fluid, 2) an opening, and 3) anejector to eject a portion of the volume of fluid through the opening.

In summary, using such an analyte capturing device 1) enables analyteconcentration via analyte-adsorbing beads; 2) enables separation of thebeads with adhered analyte thereon from a carrier fluid; 3) includes amesoscale volume to hold the analyte-adsorbing beads, the larger volumeallowing for a greater quantity of analyte-adsorbing beads; and 4)facilitates the user of larger analyte-adsorbing beads, reducing thefluidic resistance of the system and thus enhancing the analyteconcentration operation. However, the devices disclosed herein mayaddress other matters and deficiencies in a number of technical areas.

As used in the present specification and in the appended claims, theterm “fluid ejection device” refers to an individual component of theanalyte capturing device that ejects fluid. The fluid ejection devicemay be referred to as a nozzle and includes at least an ejection chamberto hold an amount of fluid and an opening through which the fluid isejected. The fluid ejection device also includes an ejector disposedwithin the ejection chamber.

Further, as used in the present specification and in the appendedclaims, the term “meso-” refers to a size scale of 100-1000 microns. Forexample, a mesofluidic layer may be between 100 and 1000 microns thick.

Further, as used in the present specification and in the appendedclaims, the term “micro-” refers to a size scale of between 10 and 100microns. For example, a microfluidic layer may be between 10 and 100microns thick and a microfluidic channel may have a cross-sectionaldiameter of between 10 and 100 microns.

Turning now to the figures, FIGS. 1A-1C are diagrams of an analytecapturing device (100) with fluid ejection devices (106), according toan example of the principles described herein. Specifically, FIG. 1A isa top view of the analyte capturing device (100), FIG. 1B is across-sectional view of the analyte capturing device (100) withoutanalyte-adsorbing beads disposed therein, and FIG. 1C is across-sectional view of a portion of the analyte capturing device (100)with analyte-adsorbing beads disposed therein. While FIGS. 1A-1C depictmultiple columns to eject waste fluid, in some examples, the fluid maybe passed downstream for further processing as depicted in FIG. 4through some or all of the columns.

As described above, the analyte capturing device (100) relies on fluidejection devices (106) for capturing analytes therein. For simplicity inFIG. 1A, just one of the fluid ejection devices (106) is indicated witha reference number. The analyte capturing device (100) also includes achamber (104). It is in this chamber (104) that analyte-adsorbing beadsare captured. That is, a solution including 1) an analyte such as DNAand 2) analyte-adhering beads that attract the analyte are received inthe chamber (104). In some examples, the size scale of the chamber (104)and the fluid ejection devices (106) are different. For example, thechamber (104) may be on a mesoscale, meaning it may be formed through asubstrate (102) with a thickness between 100 and 775 microns. The fluidejection devices (106) by comparison are on a microscale, meaning theymay be formed in a separate substrate with a thickness of between 10 and100 microns. In FIG. 1A, the fluid ejection devices (106) are indicatedin a dashed line indicating their placement below the substrate (102) inwhich the mesofluidic bead-capturing chamber (104) is formed.

FIG. 1B is a cross-sectional diagram of the analyte capturing device(100), and more specifically, a cross-sectional diagram taken along theline A-A in FIG. 1A. FIG. 1B clearly shows the first substrate (108) inwhich the fluid ejection device(s) (106-1, 106-2) are formed. In someexamples, the first substrate (108) may be formed of a polymericmaterial such as SU-8. As described above, the fluid ejection devices(106), and the first substrate (108) in which it is formed, may bemicroscopic. That is, the first substrate (108) may have a thickness ofbetween 10 and 100 microns. In some examples, the first substrate (108)may be planar and may be referred to as a microfluidic substrate due toits containing microfluidic structures.

To facilitate the ejection of fluid, each fluid ejection device (106)includes various components. For example, fluid ejection devices (106-1,106-2) include an ejection chamber (112-1, 112-2) to hold an amount offluid to be ejected, openings (114-1, 114-2) through which the amount offluid is ejected, and ejectors (110-1, 110-2), disposed within theejection chambers (112), to eject the amount of fluid through theopenings (114-1, 114-2).

Turning to the ejectors (110), the ejector (110) may include a firingresistor or other thermal device, a piezoelectric element, or othermechanism for ejecting fluid from the ejection chamber (112). Forexample, the ejector (110) may be a firing resistor. The firing resistorheats up in response to an applied current. As the firing resistor heatsup, a portion of the fluid in the ejection chamber (110) vaporizes togenerate a bubble. This bubble pushes fluid through the opening (114).As the vaporized fluid bubble collapses, fluid is drawn into theejection chamber (112) from a passage that connects the fluid ejectiondevice (106) to the bead-capturing chamber (104), and the processrepeats. In this example, the fluid ejection device (106) may be athermal inkjet (TIJ) fluid ejection device (106).

In another example, the ejector (110) may be a piezoelectric device. Asa voltage is applied, the piezoelectric device changes shape whichgenerates a pressure pulse in the ejection chamber (112) that pushes thefluid out the opening (114). In this example, the fluid ejection device(106) may be a piezoelectric inkjet (PIJ) fluid ejection device (106).

Disposed on top of the first substrate (108) is a second substrate(102). The second substrate (102) may be formed of a different material,such as silicon. The second substrate (102) defines in part the chamber(104) through which the solution is passed and in which the beads arecaptured. In some examples, the second substrate (102) may be planar andmay be referred to as a silicon substrate due to its being formed of asilicon material.

The chamber (104) may take many forms. For example, as depicted in atleast FIG. 1B, the chamber (104) may be a slot and may be funnel-shaped.The slot may be fluidly coupled to multiple fluid ejection devices. Inanother example, as depicted in FIGS. 3A-3C, the bead-capturing chamber(104) may include multiple fluid delivery holes beneath the slot, whichholes are coupled to multiple fluid ejection devices (106).

The second substrate (102) and the associated chamber (104) may be onthe mesoscale. That is, a thickness of the second substrate (102) may bebetween 100 and 775 microns thick, and the chamber (104) may have avolume of between 0.01 microliter and 10 microliters, Being on themesoscale, the chamber (104) can capture larger analyte-adhering beadsand can retain a higher quantity of the analyte-adhering beads, both ofwhich increase the efficiency of analyte concentration as describedbelow.

Moreover, the analyte capturing device (100), by using inkjet componentssuch as ejection chambers (112), openings (114), and ejectors (110)disposed within the ejection chambers (112), enables low-volumedispensing of fluids.

FIG. 1C is a cross-sectional diagram of the analyte capturing device(100) taken along the line A-A in FIG. 1A and depicts the flow of ananalyte-containing solution through the analyte capturing device (100).As described above, a solution is loaded into the analyte capturingdevice (100) and fills the chamber (104). The analyte-adhering beads(116) having a diameter greater than the microfluidic channels in thefirst substrate (108) cannot pass to the microfluidic section andtherefore aggregate in the chamber (104).

As described above, the beads (116) are components that draw, or adsorb,the analyte to their surface. For example, the beads (116) may be formedof silica, alumina, a polymer, or other material. The beads (116) may ormay not have a surface treatment that draws the analyte. The surfacetreatment may be specific to the analyte of interest. For example, aminogroups could be added to the surface of the beads (116). These aminogroups acquire a proton and thereby become positively charged, makingthem attractive to negatively charged DNA molecules.

In another example, complex proteins may be added to the beads (116)with complementary proteins on the analyte. As such, the proteins willattract one another and the analyte will aggregate on the beads (116).In some examples, the analyte-adhering beads (116) may have a diameterof between 5 and 20 microns, which may be larger than the diameter ofthe microfluidic channels.

In one example, the activation of the fluid ejection device (106)creates a fluid flow past the analyte-adsorbing beads (116). As thesolution passes the beads (116), analyte is captured therein, and theremaining solution may be expelled as waste through the opening (114) ofthe fluid ejection device (106). In another example, a carrier fluidincludes the beads (116). In this example, adsorption of the analyte onthe beads (116) occurs upstream. In this example, the beads (116) arecaptured in the chamber (104), and the fluid ejection devices (106) workto expel waste fluid. That is, in either example, the analytes in thesolution are separated from the carrier fluid.

In some examples, the solution may include a lysis buffer which breaksdown the cell membrane/walls such that the analyte in the cell can becollected. In this example, the lysis solution forms part of the carrierfluid that is expelled through the fluid ejection device (106).

Once separated from the carrier fluid, the analyte can then be passeddownstream. For example, once all the carrier fluid has been removed, anelution buffer can be passed through the chamber (104). The elutionbuffer works to break down the bonds that adhere the analyte to thebeads (116). The fluid ejection device (106) can then be activated againto draw fluid, i.e., the elution buffer with analyte, from the chamber(104) and out the opening (114) onto a desired surface, or into anotherchamber of a larger system wherein the analyte can be further analyzed.

Accordingly, the present analyte capturing device (100) provides a largevolume, i.e., on the order of 0.01 to 10 microliters, whereanalyte-adhering beads (116) are captured to filter out the analyte fromthe rest of the solution. Using such a large volume enables thecapturing of more beads (116). More captured beads (116) increases theoverall ability to capture analytes from the solution. The larger volumealso enables the use of larger analyte-adhering beads (116), such asthose having a diameter of between 5-20 microns. Larger analyte-adheringbeads (116) reduce the fluidic resistance of the system. That is,smaller analyte-adhering beads (116) packed more tightly togetherincrease the fluid resistance such that greater pressures are needed todrive the fluid through the volume. By comparison, largeranalyte-adhering beads (116) reduce the fluid resistance, such that lesspressure is required to drive the fluid. Using a lower pressure 1) mayincrease the longevity and throughput of the system, 2) is less complex,and 3) allows the use of smaller, less invasive driving mechanisms.

FIG. 2 is a flow diagram of a method (200) for analyte capturing withthe analyte capturing device (FIG. 1A, 100), according to anotherexample of the principles described herein. According to the method,analyte-adsorbing beads (FIG. 1C, 116) are received (block 201) into amesofluidic bead-capturing chamber (FIG. 1A, 104). That is, as describedabove an analyte capturing device (FIG. 1A, 100) includes a chamber(FIG. 1A, 104) that is on a mesoscale. As a specific example, the secondsubstrate (FIG. 1, 102) in which the chamber (FIG. 1A, 104) is formedmay have a thickness of between 100 and 775 microns. A reservoir offluid feeds fluid to this chamber (FIG. 1A, 104). The fluid in thereservoir may be a solution that includes an analyte, a carrier fluid,and analyte-adsorbing beads (FIG. 1C, 116) that draw the analyte fromthe solution.

The microfluidic ejection device (FIG. 1A, 106) is then activated. Doingso generates (block 202) flow through the mesofluidic chamber (FIG. 1A,104).

With a flow generated (block 202), the carrier fluid can be expelled(block 203). That is, the operation of the microfluidic ejection device(FIG. 1A, 106) expels the waste fluid, i.e., the carrier fluid andextraneous components, out of the analyte capturing device (FIG. 1A,100). Such expelling may be onto a waste surface or into a wastecontainer.

The method (200) as described herein allows for the separation ofanalyte from the carrier fluid. Specifically, the carrier fluid isexpelled as waste and the analyte is retained by the beads (FIG. 1C,116). Such a separation increases the concentration of the analyte forfurther analysis. Accordingly, the analyte capturing device (FIG. 1A,100) as described herein provides a simple and effective way toseparate, and concentrate an analyte within a solution.

FIGS. 3A-3C are diagrams of an analyte capturing device (100) with fluidejection devices (106), according to another example of the principlesdescribed herein. Specifically, FIG. 3A is a top view of the analytecapturing device (100) and FIGS. 3B and 3C are cross-sectional views ofthe analyte capturing device (100).

In this example, the analyte capturing device (100) includes the secondsubstrate (102) in which a bead-capturing chamber (104) is formed andalso includes fluid ejection devices (106). However, in this example,the bead capturing chamber (104) includes multiple bead-capturing holes(318) disposed beneath the chamber (104). For simplicity, a singleinstance of a bead-capturing hole (318) is indicated with a referencenumber. The bead-capturing holes (318) serve to capture theanalyte-adsorbing beads (FIG. 2, 116) as fluid flows therethrough. Theadditional material between the holes (318) may add to the mechanicalrigidity of the second substrate (102). For example, when the secondsubstrate (102) is thinner, it may be more susceptible to mechanicalfailure. Accordingly, the material between the holes (318) increase therigidity of the second substrate (102). In this example, the holes (318)may be any size, for example between tens of microns to a few hundredmicrons. Moreover, while FIG. 3A depicts a particular orientation ofcertain holes (318) with a certain diameter. Any number, anyorientation, and any-sized holes (318) may be used, in some exampleswith the holes (318) having different sizes.

FIG. 3B is a cross-section of the analyte capturing device (100)depicted in FIG. 3A. Specifically, FIG. 3B is a cross-sectional diagramtaken along the line B-B in FIG. 3A. FIG. 3B clearly depicts the holes(318-1, 318-2) as they feed multiple fluid ejection devices (106-1,106-2). Feeding multiple fluid ejection devices (106) via mesofluidicholes (318) may allow for faster solution processing, That is, ratherthan passing fluid to just one fluid ejection device (106), fluid can bepassed to multiple fluid ejection devices (106-1, 106-2). While FIG. 3Bdepicts two holes (318-1, 318-2) passing solution to two fluid ejectiondevices (106-1, 106-2), each hole (318) may be coupled to any number offluid ejection devices (106). The holes (318) may be of any size, forexample, the holes (318) may have diameters of between 5 and 80 microns.In this example, as has been described above, the beads (116) may besized such that they cannot pass into the microfluidic structures of thefirst substrate (108).

FIG. 3C depicts yet another example using holes (318) coupled to thechamber (104). In this example, a thin silicon membrane (320) is placedat the bottom of the chamber (104). This membrane (320) is perforatedsuch that fluid may pass through, but the beads (116) do not on accountof their larger diameter. Use of the membrane (320) as described hereinmaintains the beads (116) further away from the microscopic fluidejection devices (106) such that they do not impede the flow of fluidinto, or through, the microfluidic structures. In some examples, themembrane (320) may be formed of a silicon material or SU8 and may bebetween 3 and 20 micrometers thick.

FIG. 4 is a cross-sectional diagram of an analyte capturing device (100)with fluid ejection devices (106), according to another example of theprinciples described herein. As in examples above, the analyte capturingdevice (100) includes a first substrate (108), a second substrate (104),a bead-capturing chamber (104), and fluid ejection device(s) (106). Inthis example, the analyte capturing device (100) further includes ananalyte channel (422) in the first substrate (108). Through this analytechannel (422), the analyte, following capture, is passed to anothercomponent of the fluid analytic system. For example, once the carrierfluid has been expelled, the elution buffer described above is insertedinto the bead-capturing chamber (104) to remove the analyte from theanalyte-adsorbing beads (116), This may be done by, for example,altering the pH, changing electrical charge, and/or heating the beads(116).

In this example, a driving mechanism can direct the fluid flow throughthe analyte chamber (422) as opposed to the fluid ejection device (106).For example, a pump may be disposed at some point along the analytechamber (422), or in some examples, at the end of the analyte chamber(422). At a predetermined time, this pump or other driving mechanismcould be activated to draw the analyte and elution buffer through theanalyte channel (422) and away from the fluid ejection device (106). Inone specific example, the fluid may be drawn to another chamber orcomponent to further analyze and/or process the fluid. Doing so may bebeneficial in that it does not expose the analyte to environmentconditions, which may tarnish or otherwise contaminate the analyte.

FIG. 5 is a diagram of a method (500) for analyte capturing with theanalyte capturing device (FIG. 1A, 100), according to another example ofthe principles described herein. According to the method (500),analyte-adsorbing beads (FIG. 1C, 116) are received (block 501) in amesofluidic bead-capturing chamber (FIG. 1A, 104) and a flow generated(block 502). Excess carrier fluid is then expelled (block 503) out ofthe analyte capturing device (FIG. 1A, 100). These operations may beperformed as described above in connection with FIG. 2.

Then, as described above, the analyte may be separated from theanalyte-adsorbing beads (FIG. 1C, 116). This may be performed by drawing(block 504) an elution buffer through the analyte-adsorbing beads (FIG.1C, 116), which at this stage have analytes adhered thereon. Asdescribed above, the elution buffer breaks down the bonds that adherethe analyte to the analyte-adsorbing beads (FIG. 1C, 116).

Following removal from the analyte-adsorbing beads (FIG. 1C 116), theanalyte is then drawn (block 505) from the bead-capturing chamber (FIG.1A, 104). This may occur in a number of different ways. For example, thefluid ejection device (FIG. 1A, 106) could be activated to expel theanalyte and the elution buffer from the analyte capturing device (FIG.1A, 100) through the opening (FIG. 1B, 114). In this example, such anoperation may be conducted after the entirety of the carrier fluid hasbeen expelled. Such an example may allow for the analyte to be depositedon any type of surface or container that is external and separate fromthe analyte capturing device (FIG. 1A, 100).

In another example, a chamber pump, or some other driving mechanism isactivated to draw (block 505) the analyte and elution buffer from thebead-capturing chamber (FIG. 1A, 104) through an analyte channel (FIG.4, 422). In this example, the analyte may travel to another component ofthe analyte processing system. Using an analyte channel (FIG. 4, 422) inthis fashion, prevents the analyte from contact with the environment orusers, which may be undesirable.

FIG. 6 is a cross-sectional diagram of an analyte capturing device (100)with fluidic ejection devices (106), according to another example of theprinciples described herein. As in other examples, the analyte capturingdevice (100) includes a first substrate (108) with a fluid ejectiondevice (106) formed therein and a second substrate (102) with abead-capturing chamber (FIG. 1A, 104) formed therein. In this example,the analyte capturing device (100) includes a third substrate (624)having an opening larger than the bead-capturing chamber (FIG. 1A, 104),This third substrate (624) opening allows for even a greater volume intowhich analyte-adsorbing beads (116) are collected. That is, thebead-capturing chamber (FIG. 1A, 104) by itself may have a volume of0.01 to 10 microliters. In this example, the size and shape of theopening in the third substrate (624) may increase the volume to upwardsof 100 microliters. The increased volume allows for an even largerquantity of analyte-adsorbing beads (116) to be captured therein andfurther reduces the fluidic resistance as the beads (116) may be lesstightly packed. In some examples, the third substrate (624) may beformed of any material including another silicon layer, a plastic, aceramic, or a composite layer.

FIG. 7 is a top view of an analyte capturing device (100), according toanother example of the principles described herein. To accommodate thecapture of more beads (FIG. 1C, 116) thus even further increasing theefficacy of analyte concentration, the analyte capturing device (100)may include multiple bead-capturing chambers (104). While FIG. 7 depictstwo bead-capturing chambers (104-1, 104-2), the analyte capturing device(100) may include any number of bead-capturing chambers (104). Usingmultiple bead-capturing chambers (104) also increases the flow rate ofthe solution through the analyte capturing device (100), which increasedflow rate also decreases processing times.

In some examples, the different chambers (104-1, 104-2) may havedifferent dimensions, shapes, and/or profiles. Using chambers (104-1,104-2) with different parameters increases the customization availableon an analyte capturing device (100). For example, the differentchambers (104-1, 104-2) may be used to analyze different solutions.Thus, the present analyte capturing device (100) provides for customizedand tailored chemical analysis.

In summary, using such an analyte capturing device 1) enables analyteconcentration via analyte-adsorbing beads; 2) enables separation of thebeads with adhered analyte thereon from a carrier fluid; 3) includes amesoscale volume to hold the analyte-adsorbing beads, the larger volumeallowing for a greater quantity of analyte-adsorbing beads; and 4)facilitates the user of larger analyte-adsorbing beads, reducing thefluidic resistance of the system and thus enhancing the analyteconcentration operation. However, the devices disclosed herein mayaddress other matters and deficiencies in a number of technical areas.

What is claimed is:
 1. An analyte capturing device, comprising; a firstsubstrate having microfluidic channels disposed therein; a secondsubstrate disposed on top of the first substrate; a chamber disposedthrough the second substrate to capture beads that adsorb analytes; andat least one fluid ejection device disposed in the first substrate todraw an analyte-containing solution through the beads disposed withinthe chamber.
 2. The device of claim 1, wherein the chamber is a slotfluidly coupled to multiple fluid ejection devices.
 3. The device ofclaim 2, wherein the chamber comprises multiple holes disposed betweenthe slot and the multiple fluid ejection devices.
 4. The device of claim1, further comprising a perforated membrane disposed between the firstsubstrate and the second substrate to prevent beads from entering themicrofluidic channels of the first substrate.
 5. The device of claim 1,wherein: the second substrate has a thickness of between 100 and 775microns; and the chamber has a volume of between 0.01 microliter to 10microliters.
 6. The device of claim 1, further comprising an analytechannel in the first substrate to direct the analyte, following capture,away from the chamber.
 7. The device of claim 1, further comprising athird substrate disposed on the second substrate to capture additionalbeads.
 8. A method comprising: capturing beads which adsorb analytes ina mesofluidic chamber of an analyte capturing device; activating amicrofluidic fluid ejection device to generate a flow through themesofluidic chamber; and expelling a carrier fluid from the analytecapturing device.
 9. The method of claim 8, further comprising drawingan elution buffer through the beads to remove the analyte from thebeads.
 10. The method of claim 9, further comprising activating themicrofluidic fluid ejection device to expel the analyte and elutionbuffer from the analyte capturing device.
 11. The method of claim 9,further comprising activating a chamber pump to draw the analyte andelution buffer away from the chamber.
 12. An analyte capturing device,comprising: a planar microfluidic substrate having microfluidic channelsdisposed therein; a planar silicon substrate disposed on top of theplanar microfluidic substrate; at least one mesoscale chamber disposedthrough the planar silicon substrate to capture beads therein, whichbeads adsorb analytes; and a microscale fluid ejection device disposedin the planar microfluidic substrate to draw an analyte-containingsolution through the beads disposed within the chamber, wherein thefluid ejection device comprises: an ejection chamber to hold a volume offluid; an opening; and an ejector to eject a portion of the volume offluid through the opening.
 13. The device of claim 12, furthercomprising the beads which adsorb analytes disposed within the chambers,wherein: the beads have a surface treatment selected based on theanalyte; and a diameter of the beads is between 5 and 20 microns. 14.The device of claim 12, wherein the at least one mesoscale chambercomprises multiple mesoscale chambers.
 15. The device of claim 14,wherein the multiple mesoscale chambers have at least one of differentdiameters and different cross-sectional areas.